Johnson has averaged 5.8 total rebounds per game over his career, including 3.6 defensive boards per game, but has only logged 2.7 defensive rebounds per game and 4.3 overall this season. His blocks per game have historically been at 1.1 per game, but are just over half that rate so far this year at .6 per game. And while his job with Boston has primarily been as defensive anchor, his lack of mobility and court awareness (and habits of not boxing out OR getting boards) has made his dip in offense even more of a problem than it should be.

He’s only scoring 1.2 points less than his career average of 7.5 points per game, but it’s the misses that are the problem; his effective field goal (EFG) percentage of .544 is the worst of his career, and it isn’t because he’s shooting more threes - he’s actually hitting on enough that it is improving his EFG percentage. Still, just under one per game at a .429 clip is not enough to change his gravity in scouting reports, and his growth as a facilitator - nearly doubling his career average of 1.2 to 2.1 per game - while useful, doesn’t justify his continuing presence in the starting lineup.

Amir Johnson must have the slowest, most meticulous shot from 3-point range in NBA history. Teams basically beg him to take it. #Celtics

Kelly Olynyk was hoped to have a breakout (OK, contract) season, but has not exactly impressed with his performance since coming back from his shoulder injury, a few outings excepted. Overall, he’s taken small steps back or held steady in pretty much every relevant category except free throws - which he’s been taking less of per game, negating any advantage the boost in makes offers, and looking more hesitant than ever in recent games at just the moment he should be doing the opposite.

So much for the obvious candidate.

Tyler Zeller has also been something of a disappointment, yet has still been outperforming Johnson as a rim protector, trailing only Al Horford’s probably unsustainable 2.6 per game by 1.7. He’s a worse rebounder and scorer than either Kelly or Amir, though, so probably can’t be expected to make good use of his single starter-level skill (shot blocking) paired with the team’s best rim protector (Horford), who won’t be on the second unit any time soon.

Tyler Zeller gotta pump fake, use the other hand, something. He gets blocked way too much for a 7-footer. #Celtics#Pelicans

Now it gets tricky, because solutions would require boosting minutes of people likely seeing little time for a reason, or playing guys out of their usual position.

Jae Crowder, interestingly, has been outrebounding Amir, Kelly and Tyler, and is on par with Amir as a rim protector, behind only Horford. Moving Jae to the four could work (assuming Horford is willing to nominally play center), but then who moves to the three?

We have seen some issues with the “IT and D” (Isaiah Thomas, Avery Bradley, Marcus Smart plus Crowder and Horford) lineup, suggesting it works best as a transition approach to confuse and stymie opponents on defense, and the rookie-scale players just don’t have the tools (yet) to seriously be even the worst starter on the floor. So, this leaves only a few candidates:

Jonas Jerebko won’t help much on defense, but should be capable (and tall) enough to help on team defense and switching, packing enough offensive gravity to keep opponents engaged, especially if his confidence builds with more minutes, as it did late last year.

Gerald Green would be another option, with greater skill on the offensive end of the floor in terms of scoring and facilitating, but would turn the ball over much more often, and is one of the team’s worst defensive players.

In this iteration, I have Zeller as the second 5 in the depth chart over Olynyk because he offers a presence as a shot blocker for an offense- and motion-oriented second unit that would be dangerously bad at defense without fringe- starter level skills in that area. Pitching Horford at moving to the five in this scenario might be a challenge, but Jerebko and Crowder could take turns switching onto centers depending on matchups, allowing Horford to be a mobile defender as he seems to prefer and excel at in this stage of his career.

What do you think, Celticslife readers? Would this - or something like it - help some of the issues caused by Boston’s underwhelming big men? Or should they get a little more time before we start to shake things up? Let us know your take in the comments.